The *Red Mars* / *Green Mars* / *Blue Mars* trilogy by Kim Stanley Robinson describes the process of terraforming Mars so that humans could live there. Could those same techniques work on other planets in the solar system? 

For example, could those techniques work on a gaseous planet such as Saturn? Or do they require solid ground? Similarly, could they work on a planet with a dense atmosphere such as Venus, or is that planet too dissimilar to Mars to work without major changes?